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Related Concept Videos

Gene Duplication and Divergence02:37

Gene Duplication and Divergence

The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was  generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Genetic Drift03:33

Genetic Drift

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...
Genetic Variation01:25

Genetic Variation

Genetic variation is the diversity in DNA sequences found among individuals of the same species. This diversity is crucial for a species' survival because it helps organisms adapt to environmental changes. Genetic variation begins with fertilization, where an egg and sperm cell merge. Each of these cells carries 23 chromosomes, up to 46 in the fertilized egg. Chromosomes are long DNA strands that contain genes, the basic units of heredity.
Genes exist in different versions called alleles, which...
Mutation, Gene Flow, and Genetic Drift01:09

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
Conservative Site-specific Recombination and Phase Variation02:53

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
Genetic Screens02:46

Genetic Screens

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Related Experiment Video

Updated: Jul 6, 2026

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
06:18

Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR

Published on: July 11, 2025

Repetitive genetic inversion of optical extinction data.

B R Lienert, J N Porter, S K Sharma

    Applied Optics
    |March 25, 2008
    PubMed
    Summary

    Deriving aerosol size distributions using genetic inversion can lead to nonunique results. Many different distributions may fit extinction data, highlighting the need for caution with existing measurements.

    Area of Science:

    • Atmospheric Science
    • Aerosol Science
    • Computational Physics

    Background:

    • Accurate aerosol size distributions are crucial for climate modeling and air quality assessments.
    • Multiwavelength extinction measurements are commonly used to infer aerosol properties.
    • Previous methods often assume unique solutions, potentially overlooking ambiguities.

    Purpose of the Study:

    • To develop and evaluate a genetic inversion method for deriving aerosol size distributions.
    • To assess the uniqueness and reliability of size distributions obtained from extinction data.
    • To determine the precision required in extinction measurements for robust distribution recovery.

    Main Methods:

    • Employing a genetic algorithm to search for log-normal size distribution parameters.

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    Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR
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  • Utilizing multiwavelength extinction measurements as input data.
  • Repetitively applying the genetic inversion with varying random seeds to explore solution space.
  • Main Results:

    • Demonstrated that multiple, dissimilar log-normal size distributions can equally fit extinction data.
    • Showed that high precision (0.5% misfit at 10 wavelengths) is needed to resolve bimodal distributions.
    • Highlighted significant nonuniqueness in aerosol size distributions derived from typical extinction measurements.

    Conclusions:

    • Aerosol size distributions derived from extinction data can be highly nonunique.
    • Existing inversion techniques may yield ambiguous results, necessitating cautious interpretation.
    • Improved measurement precision and advanced inversion strategies are needed for reliable aerosol characterization.